1. Field of the Invention
The present invention relates to an ink set and, more particularly, to an ink jet recording method and an ink jet recording apparatus using an ink jet method, as well as an ink set suitably used for an image formation method.
2. Related Background Art
It has conventionally been known that an ink (pigment ink, etc.) that contains a water-insoluble coloring material as colorant produces an image excellent in toughness including water resistance, light resistance, and the like. In recent years, various techniques have been proposed for the purposes of further increasing the optical density of the image formed by such an ink and effectively suppressing occurrence of bleeding at the boundaries between different color regions in the case where recording of a color image in which the respective color-regions are situated adjacently to one another is performed. For example, a technique of further increasing the image density by using an ink containing a self-dispersible carbon black and certain salt has been proposed (refer to, for example, Japanese Patent Application Laid-Open No. 2000-198955).
Also proposed is a technique of attaching an ink jet recording ink which is a composition containing a pigment, a polymer particle, a water-soluble organic solvent, and water and aqueous solution containing polyvalent metal salt to a recording medium, followed by reaction of the ink composition with the aqueous solution containing polyvalent metal salt to form a high-quality image (refer to, for example, Japanese Patent Application Laid-Open No. 2000-63719). In either case, the pigment existing, in a dispersed state, in the ink is forcibly agglomerated on the surface of the recording medium to suppress permeation of the pigment into the recording medium, thereby further increasing the image density and further suppressing the bleeding in the image, as compared to the case of the image obtained by using a conventional pigment ink.
As described above, means of adding a special compound such as one that prompts the pigment in the ink to become massed together, reacting two or more types of liquid components, or the like has been mainly used to obtain a high-quality image in which the density thereof is increased and occurrence of the bleeding is suppressed.